Optimisation of low-dose CT with adaptive statistical iterative reconstruction in total body examination.

PURPOSE: The aim of this study was to assess the feasibility of low-dose computed tomography (CT) with the adaptive statistical iterative reconstruction (ASIR) algorithm in whole-body imaging with low tube voltage and current. MATERIALS AND METHODS: Twenty-three patients underwent whole-body CT with 40% of ASIR and parameters modulated according to body mass index (BMI). All had previously undergone conventional-dose CT with 100% filtered back projection (FBP). Two radiologists jointly assessed image quality (sharpness, noise, artefacts) and diagnostic quality blinded to the scanning technique. The effective dose and image quality obtained with the ASIR protocol were compared with those obtained with the FBP algorithm. RESULTS: The mean effective dose achieved with ASIR was 15.6 ± 5 mSv versus 21.8 ± 5.3 mSv with the FBP protocol (p<0.0001). Image quality was good in all low-dose CT scans, and diagnostic quality was comparable with or superior to that of conventional-dose CT. CONCLUSIONS: Low-dose CT with the ASIR algorithm is feasible and ensures significant reduction in effective dose.

Thermophoresis of DNA determined by microfluidic fluorescence.

We describe a microfluidic all-optical technique to measure the thermophoresis of molecules. Within micrometer-thick chambers, we heat aqueous solutions with a micrometer-sized focus of infrared light. The temperature increase of about 1 K is monitored with temperature-sensitive fluorescent dyes. We test the approach in measuring the thermophoresis of DNA. We image the concentration of DNA in a second fluorescence-color channel. DNA is depleted away from the heated spot. The profile of depletion is fitted by the thermophoretic theory to reveal the Soret coefficient. We evaluate the method with numerical 3D calculations of temperature profiles, drift, convection and thermophoretic depletion using finite element methods. The approach opens new ways to monitor thermophoresis at the single molecule level, near boundaries and in complex mixtures. The flexible microfluidic setting is a good step towards microfluidic applications of thermophoresis in biotechnology.